fix copyright years on source files; all functions in browser.c were

fix copyright years on source files; all functions in browser.c were
originally added in 2001; the oldest function in color.c is
do_colorinit() (now color_init()), which was originally added in 2001;
the oldest function in chars.c is revstrstr(), which was originally
added in 2001; the oldest function in help.c is do_help(), which was
originally added in 2000; the oldest function in prompt.c is statusq()
(now do_prompt()), which was originally added before 0.6.6, which was
apparently in 1999; all functions in rcfile.c were originally added in
2001; one of the oldest functions in search.c is do_search(), which was
originally added in 0.2.7, which was apparently in 1999; and one of the
oldest functions in text.c is do_wrap(), which was originally added in
0.3.1, which was apparently in 1999; also, for functions originally
adapted from other sources, add notices from the original files, as we
do with the tab completion functions adapted from busybox

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@3172 35c25a1d-7b9e-4130-9fde-d3aeb78583b8